In a substrate processing apparatus, which includes a processing chamber that accommodates a wafer for a semiconductor device (hereinafter, simply referred to as “wafer”) serving as a substrate and performs a plasma process on the wafer with plasma generated within the processing chamber, the plasma needs to be uniformly distributed in a processing space facing the wafer within the processing chamber in order to perform a uniform plasma process on the wafer.
Distribution of the plasma depends on distribution of a processing gas in the processing space. Thus, there has been suggested a substrate processing apparatus in which a processing space is divided into multiple regions and flow rates of processing gases to be introduced into the respective regions are controlled (see, for example, Patent Document 1).
In the substrate processing apparatus, there are formed multiple gas diffusion spaces respectively corresponding to multiple regions divided within a shower head facing the processing space. A processing gas supplied into each of the gas diffusion spaces is introduced into each of the regions through multiple gas holes. By controlling a flow rate of the processing gas to be supplied into each of the gas diffusion spaces, a flow rate of the processing gas to be introduced into each of the respective regions can be controlled.
Further, in order to uniformly distribute the processing gas in each of the regions, it is desirable to uniformly distribute the processing gas in each of the gas diffusion spaces. Thus, it has been suggested that multiple gas supply openings for supplying the processing gas into the gas diffusion spaces are arranged in a symmetrical or uniform manner with respect to a center of the gas diffusion space and distances of gas supply paths from a gas supply source to the respective gas supply openings are all the same (see, for example, Patent Document 2).
In Patent Document 2, as depicted in FIG. 24, there is provided a plate-shaped manifold (gas distribution plate) 251 including multiple gas supply openings 250a and 250b which are uniformly arranged to penetrate through the manifold. Further, gas supply grooves 252a and 252b, which are branched, are formed on an upper surface of the manifold 251. In the respective gas supply grooves 252a and 252b, distances from communicating portions 253a and 253b with a gas supply source (not illustrated) to the gas supply openings 250a and 250b, respectively, are set to be all the same.
Thus, the processing gas can be supplied from the gas supply openings 250a at the same timing and at the same pressure. Further, the processing gas can be supplied from the gas supply openings 250b at the same timing and at the same pressure.